Examples of the infusion pump include a finger-type (peristaltic) infusion pump. The finger-type infusion pump is of the type that sends an amount of infusion solution by driving the infusion tube, which is positioned between a plurality of fingers and a tube pressing plate (pressing plate), to advance and retract and then compressing the infusion tube sequentially with each finger, which is also referred to as a “full-press type”. It is problematic that in such full-press type infusion pumps, any settling (flat deformation) of the infusion tube may be occurred, resulting in the reduction in the rate of infusion per unit time.
As a solution for reducing the settling of the infusion tube, a midpress-type (half-occlusion type) infusion pump is proposed (see Patent Document 1, for example). In the infusion pump described in the Patent Document 1, the settling of the infusion tube is reduced by providing a plurality of fingers each of which can be drive the fingers individually in a pump mechanism, pressing the infusion tube in a manner that only the upstream and downstream sides of the infusion tube are fully collapsed while the intermediate portion of the infusion tube between the upstream and downstream sides is not fully collapsed, i.e., it is halfway collapsed. According to this half-occlusion type infusion pump, although the reduction in the rate of infusion can be improved, it is not possible to completely eliminate the reduction of the rate of infusion.
As a technique of forcedly restoring the settling of the tube or the like, there is a tube restoring technique comprising a primary finger which presses a tube and a secondary finger which is moved in a direction orthogonal to a pressing direction for the primary finger, wherein the tube is restored by the secondary finger (see Patent Document 2, for example). In such techniques, as the method of driving the secondary finger, there is a method wherein the secondary finger is connected to the primary finger via a link mechanism and the secondary finger is driven in conjunction with the driving of the primary finger. In addition, as the other driving method, there are the method wherein the primary finger and the secondary finger are driven individually, the method wherein each of the primary and secondary fingers is cam-driven and two cam shafts are connected via a timing belt to drive the primary finger and the secondary finger, and the like.